यदि x - √x = 20 है; √x का मान ज्ञात कीजिये। A. 5 B. 6 C. 8 D. 7

Let √x = t, so t² − t − 20 = 0, i.e. (t − 5)(t + 4) = 0. A square root cannot be negative, so √x = 5 (x = 25).